The Mouse Models Resource (MMR) provides TJL Cancer Center investigators with access to approximately 800 of the 2,900 publicly available strains available from TJL's Genetic Resource Repository. The MMR also provides information about these strains, and the expertise of scientists in the Genetic Resource Program. The live Resource, together with Resource strains available from the Cryopreservation Resource comprises the Genetic Resource Repository and is the largest single collection of genetically defined mouse strains anywhere in the world. The Mouse Models Resource provides TJL Cancer Center members with small numbers of mice from the Repository free of charge. Cancer Center members can obtain breeding pairs and small numbers of mutants and controls from mutant strains, or individual mice from strain panels. Cancer Center members add value to the strains by further characterizing them;this scientific information is added to the strain information database from resulting publications or by electronic transmission directly into the Mouse Phenome Database for strain panels. The Resource contains mouse strains carrying spontaneous, induced, and genetically engineered mutations; mice with chromosome aberrations;and special inbred strains and strain panels, including wild-derived inbred, congenic, Recombinant Inbred (Rl), and consomic strains. For insurance against loss and economic management of very low demand strains, all strains are cryopreserved as embryos or gametes through the Reproductive Sciences program, and DNA from most strains is available through the Mouse DNA Resource in Genome Sciences. Genetic Resource Technical Information Scientists gather, curate, and maintain the operational and scientific information about these strains. Mouse Models Resource personnel provide genetic expertise and advice, and colony maintenance advice, including special husbandry needs and biological information, about the mice in the Resource. Resource personnel also provide a core of geneticists who have many years of experience and extensive knowledge and expertise in a variety of areas related to gene mapping, mouse genetics, and mouse husbandry and biology. The MMR occupies 7,345 ft2 of vivarium and procedure space in Building 32 and the Functional Genomics Building. Dr. Muriel Davisson, Senior Staff Scientist, Director of Genetic Resources, is the Project Leader responsible for administration and coordination of Mouse Models Resource programs with each other and with other Resources and Scientific Services at TJL.